Diode-cladding-pumped Yb³⁺, Ho³⁺-doped silica fiber laser operating at 2.1-μm

The characteristics of the performance of a diode-cladding-pumped Yb³⁺, Ho³⁺-doped silica fiber laser are presented. To our knowledge this is the first demonstration of a Yb³⁺, Ho³⁺-doped fiber laser, and a maximum output power of 0.85 W was achieved for a launched pump power of 10.9 W. For launched pump powers <7W, the slope efficiency was 12.5%. Visible fluorescence emission with peaks at 485, 550, and 660 nm measured at the output from the laser suggests that excited-state absorption and energy-transfer upconversion losses may impair the functioning of the laser. Increasing the Yb³⁺and Ho³⁺concentrations and the Yb³⁺:Ho³⁺concentration ratio may lead to an improvement in the overall efficiency of the device.